During gas and oil drilling, thousands of gallons of drilling mud, fracturing chemicals and flowback water are on site. Many operating companies compact the pad site and place a liquid-proof liner over 30,000 to 120,000 square feet of surface. Around the perimeter of the containment area, the liner can be pulled over a raised row of dirt, railroad ties, corrugated pipe, foam block, or rubber/plastic forms to provide sidewalls, also known as berms. The liner in conjunction with the berms contains the leaks and spills that might happen on the site so that vacuum trucks can remove the waste without impact to the environment. The sump capacity of the containment is determined by multiplying the area of liner by the berm height.
There are many issues with the current berm options. An earthen berm requires heavy equipment to build. The liner cannot be directly attached and requires staking, which is subject to wind uplift and tearing. The earthen berms also flatten under repeated vehicle traffic.
Although railroad ties can be moved from site to site for reuse, they are difficult to decontaminate since they are absorbent to the chemicals on site. Because they are rectangular, they require metal or earthen ramps on both sides to accommodate bobcats, skid steers, front end loaders, and track hoes on and off the containment area. Any earthen ramp inside the containment area absorbs the chemicals and must be landfilled afterwards. To accommodate tractor trailer traffic, the railroad ties must be completely removed. Since durable liners are able to survive multiple operations during well construction, the berms may be removed and reinstalled up to five times. While the railroad tie berms are out of position, the containment has an open sidewall and negligible sump capacity. If a release occurs during that period, the liquids may flow off the containment.
Corrugated pipe is easy to decontaminate due to its plastic construction. It is also light weight and easy to move. It is, however, easily crushed and is unable to support a ramp. It does not provide a substantial physical barrier to traffic in sensitive areas and cannot be used in drive-over areas.
Triangular, circular and rectangular foam blocks underneath the liner provide berms that are crush resistant while also light weight. Containing the foam within a liner pocket prevents the foam from being pushed into the pad. To control wind uplift and foam migration out of the pocket, rock is placed on the liner tail outside the berm. While foam is the preferred berm for many operators, the liner on the berm is exposed to ongoing damage.
Another option is a plastic or rubber forms. Examples are 6 inch Muscle Walls from Muscle Wall Holding, LLC in Logan, Utah, and a rubber slotted base and key as disclosed in U.S. patent application Ser. No. 13/688,517. Again in both cases, the liner is pulled over the berms and is subject to ongoing damage. The first example, the plastic form from Muscle Wall, was designed for drive-over traffic but requires the liner to be exposed on the berm surface. The rubber form from U.S. patent application Ser. No. 13/688,517 requires ramps on drive-over sections since the rubber disintegrates under traffic. The rubber forms are also extremely heavy at around 200 pounds each and require a skid steer or multiple people to place.
In current methods mentioned above, the containment liner is pulled over the berm. It is thereby directly exposed to drive-over traffic and the associated punctures and tears that result from heavy equipment, fork tines, tires, etc. If a tear or puncture of the liner on the berm is inside the containment area, the overall sump capacity is reduced to the lowest point of the tear or puncture, requiring repair.